39991 ÷ 9 = 4443 R4
We're going to perform division on 39991 with 9 as the divisor.

Step 1:
9 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 3 to get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 9

Step 2:
9 goes into 39 4 times with a remainder of 3.
Write down 4 as next digit of of the result. 
Result so far: 4
Subtract 36 from 39 to get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 9

Step 3:
9 goes into 39 4 times with a remainder of 3.
Write down 4 as next digit of of the result. 
Result so far: 44
Subtract 36 from 39 to get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 9

Step 4:
9 goes into 39 4 times with a remainder of 3.
Write down 4 as next digit of of the result. 
Result so far: 444
Subtract 36 from 39 to get 3.
Bring next digit (1) of the dividend behind the 3 and repeat the process: 31 / 9

Step 5:
9 goes into 31 3 times with a remainder of 4.
Write down 3 as next digit of of the result. 
Result so far: 4443
Subtract 27 from 31 to get 4.

The final result is 4443 with a remainder of 4.